The present invention relates to a modified hydrogen peroxide and to its use in the chemical sterilization of packaging materials. Chemical sterilization of packaging materials currently makes it possible to make foodstuffs such as milk, yoghurt or fruit juices available to the end user in simple, user-friendly packaging, without treating or impairing the respective foodstuff itself in any way. The high degree of acceptance of such user-friendly packaging results in the filling capacity of the filling machines constantly being increased, which simultaneously is often accompanied by shortening of the filling cycles.
In the chemical sterilization of packaging materials, the chemicals which can be used are limited by food regulations. Only those chemicals or mixtures which are permitted on their own or—in the case of mixtures—the individual constituents of which are permitted under food regulations are permitted to be used.
It has been shown in the past that hydrogen peroxide, as a result of its high oxidizing capacity, is a very effective germicidal medium. Consequently, hydrogen peroxide has now been used successfully for years in almost all aseptic packaging plants in the milk-processing industry and also in juice production etc.
Compared with other germicidal substances or comparable oxidizing agents, hydrogen peroxide has the great advantage of not leaving any residues other than water behind on the packaging materials as a result of the product and of the process, apart from the slight traces of stabilizer.
In the current state of the art of chemical sterilization of packaging materials, essentially two processes have become established on the market, the dip bath process and the spray process. In both these processes, hydrogen peroxide is used as a germicidal agent at elevated temperatures. The demands made on the material-specific properties of the hydrogen peroxide depend on the process in question.
Thus, for example, in the spray process the hydrogen peroxide used should for process-related reasons contain only few “inert materials”, which very largely originate from the stabilizers used because in the spray process the “inert materials” result in incrustations in the evaporator or spraying section, which necessitates cleaning and ultimately reduces the filling capacity of the system.
In the dip bath process the germicidal process takes place in a bath filled with hydrogen peroxide. For this, the packaging material is passed through a temperature-controlled bath and during the later course of the process is mechanically separated from adhering hydrogen peroxide residues. As a result of the process, therefore, the hydrogen peroxide used must be more highly stabilized than the product used in the spray process referred to above.
In order to extend the useful life of the hydrogen peroxide used, foodstuff-compatible stabilizers are added to the hydrogen peroxide. It is for example known to use pyrophosphates/phosphoric acid in combination with stannates for stabilization.
The increases in filling capacity described above, with substantially unaltered dip bath geometries, are accompanied by a reduction of the residence time of the packaging material in the dip bath. In order nevertheless to maintain the sterilization effect, it is necessary to increase the operating temperature in the dip bath.